The present invention relates to a process for producing L-isoleucine by culturing a microorganism belonging to the genus Escherichia and having resistance to S-(2-aminoethyl)-L-cysteine or D-serine and an ability to produce L-isoleucine. L-Isoleucine is an amino acid which is useful as a medicament, a food additive and an additive for animal feed.
With respect to the direct fermentation process for production of L-isoleucine, various processes have been known; for example, a process by the use of a microorganism belonging to the genus Brevibacterium or Corynebacterium and having resistance to .alpha.-amino-.beta.-hydroxyvaleric acid, with additionally imparted resistance to one or more agents selected from ethionine, .beta.-(2-thiazolyl)-DL-alanine and S-(2-aminoethyl)-L-cysteine (Japanese Published Unexamined Patent Application No. 101582/75); and a process by the use of a microorganism belonging to the genus Corynebacterium and having resistance to S-(2-aminoethyl)-L-cysteine (Japanese Published Unexamined Patent Application No. 61290/77).
An efficient process for producing L-isoleucine is always in demand from an industrial viewpoint.